1. Field of the Invention
This invention relates in general to certain new and useful improvements in a lacquer composition for application to plastic articles, and more particularly, to a water based lacquer composition which provides good adherence and excellent scratch and abrasion resistance, as well as methods of making and using the composition.
2. Brief Description of the Prior Art
Many plastic parts and articles are commonly fabricated from acrylics and polyurethane due to the ease of molding or other forming and the low cost involved. In many cases where these parts or articles are primarily visually apparent to the public or in cases where aesthetic appearance is an important factor, it may be necessary to apply a dye or varnish to the exterior surface thereof. The dye or varnish also provides an important contribution in that it provides surface protection and protects the part from abrasions or scratches.
Molded plastic components of this type are widely used in a large number of industries and including, for example, the shoe industry. In this case, a shoe sole or for that matter a shoe upper may be molded from an acrylic or a polyurethane. The color of the article thus produced in the molding operation may be approximately that which is desired. However, it may be important to provide a different hue or tone to the color, in which case a dye or varnish must be applied. Further, where there is a slight surface texture to the article, it is important to apply a dye or varnish which will adhere well but will not. otherwise obliterate the surface texture.
There are numerous dyes or varnishes, often referred to as lacquers, which can be applied to the plastic articles usually by dipping, spraying or hand painting. However, in essentially all case, the dyes are organic solvent based, that is, the lacquers contain an organic solvent as a carrier. A dye or pigment included in the composition is applied to the surface of the plastic item when the solvent dried. When the plastic is not yet completely hardened, the dye or pigment becomes effectively integral with the surface of the plastic item.
In recent years, there has been an increased emphasis on environmental pollution and a strong governmental resistance to products which are hazardous to worker's health from a standpoint of pollution or which are hazardous as a result of potential fire. Most of the organic solvents employed in present day lacquers usually have a low ignition temperature and hence they are dangerous as a result of their potential to start fires. Furthermore, and in recent years, there has been increased findings of health problems associated with many of the commercial organic solvents which were at one time thought to be relatively harmless.
In view of these problems, there have been recently enacted governmental restrictions on the use of the commercial solvents such as those solvents normally used as a carrier for the lacquer compositions. These restrictions result in the necessity for spray booths, special restrictions on the amount of solvents which can be used and like factors. As a result, they substantially add increased costs to the production of the part or article.
There has been a long felt need, and which has become particularly pronounced in recent years for a water base liquid carrier used in lacquer compositions to avoid the problems associated with the organic solvent based lacquer compositions. One of the main problems which have been encountered in attempts to use a water based lacquer is the fact that there is little adhesion to the plastic parts. Previous attempts to employ a water based lacquer resulted in low adhesion and in addition, these lacquers did not provide the strength and surface resistance necessary to avoid abrasions and scratches.